Device and method for treatment of incision or hernia

ABSTRACT

Devices and methods for treating an abdominal incision or hernia are described. An implant for the restoration or prophylactic treatment of an abdominal wall comprises an elongate element and at least one sheet connected to the elongate element along a longitudinal axis of the elongate element. The elongate element is positioned along the line of incision, and the at least one sheet is secured to the abdominal muscles surrounding the incision.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/714,606 filed Dec. 14, 2012, which claims the benefit of priority toU.S. patent application Ser. No. 12/828,452 filed Jul. 1, 2010, andissued as U.S. Pat. No. 8,357,172, which claims the benefit of priorityto U.S. Prov. App. No. 61/222,691 filed Jul. 2, 2009, each of which isincorporated herein by reference in its entirety.

This disclosure relates generally to devices and methods for treatingabdominal incisions or defects, and more particularly, to prostheticdevices for treating midline incisions or hernias.

BACKGROUND

Most surgical incisions can be closed using only sutures. However,closing an abdominal incision in patients suffering from gross abdominalwall loss, particularly loss of viable fascial tissue, due, for example,to prior surgeries or necrotizing infection, can be challenging. Inaddition, some patients may be prone to dehiscence and/or herniationafter surgery due to structural defects or disease.

Currently, repair of abdominal wall incisions not amenable to primarysuture closure is sometimes performed using a synthetic mesh (such as,polypropylene, prolene, polytetrafluroethylene meshes, etc.) toreinforce the fascia and restore abdominal wall continuity. However, formany patients, incision closure and treatment of abdominal wall defectsremains difficult, particularly due to the complications resulting fromsynthetic mesh use, such as enteric fistulae formation and infection,which weaken the integrity of the incision closure.

The present disclosure provides methods and devices for improved closureof surgical incisions and/or repair of abdominal wall defects.

SUMMARY

In one aspect of the present disclosure, a device for treating abdominalincision or hernia is provided. The device comprises an elongate elementhaving a first longitudinal axis and at least one sheet connected to theelongate element along the first longitudinal axis, wherein the at leastone sheet comprises a porous biocompatible material and the elongateelement has a strength that is at least equal to that of the at leastone sheet.

In another aspect of the present disclosure, a method for treating amidline incision is provided. The method includes providing an implantcomprising an elongate element having a first longitudinal axis and atleast one sheet connected to the elongate element along the firstlongitudinal axis. The elongate element is positioned along the midlineincision, and the at least one sheet is positioned on the anteriorand/or posterior sides of rectus abdominis muscle surrounding themidline incision.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate methods and embodiments of theinvention and together with the description, serve to explain theprinciples of the various aspects of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A shows an exemplary embodiment of an implant for treatment of anincision or hernia;

FIG. 1B is a cross-sectional view of the embodiment depicted in FIG. 1Ataken along line AA′;

FIG. 1C depicts an alternate configuration of the implant depicted inFIG. 1A;

FIG. 1D is a cross-sectional view of the configuration depicted in FIG.1C taken along line BB′;

FIG. 2A is a cross-sectional view of the abdominal wall;

FIG. 2B illustrates an outline of a midline abdominal incision;

FIG. 3A shows a method of positioning an implant in the abdominal wallfor a midline incision closure, in accordance with an exemplaryembodiment of the present disclosure;

FIG. 3B illustrates an alternate method of positioning an implant in theabdominal wall for a midline incision closure, in accordance with anexemplary embodiment of the present disclosure;

FIG. 4 illustrates a method of suturing an implant to the abdominal wallfor a midline incision closure, in accordance with an exemplaryembodiment of the present disclosure; and

FIG. 5 is a flowchart showing the steps of treating an abdominalincision using an exemplary implant of the present disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference will now be made in detail to embodiments consistent with thepresent disclosure, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

In this application, the use of the singular includes the plural unlessspecifically stated otherwise. In this application, the use of “or”means “and/or” unless stated otherwise. Furthermore, the use of the term“including”, as well as other forms, such as “includes” and “included”,is not limiting. Also, terms such as “element” or “component” encompassboth elements and components comprising one unit and elements andcomponents that comprise more than one subunit, unless specificallystated otherwise. Also the use of the term “portion” may include part ofa moiety or the entire moiety. Additionally, in this application, theterms “rectus sheath” and “rectus fascia” may be used interchangeably,unless specifically stated otherwise.

The section headings used herein are for organizational purposes onlyand are not to be construed as limiting the subject matter described.All documents, or portions of documents, cited in this application,including but not limited to patents, patent applications, articles,books, and treatises, are hereby expressly incorporated by reference intheir entirety for any purpose.

The present disclosure provides methods and devices for effectiveincision closure following a surgical procedure and/or abdominal walltreatment for structural abdominal wall defects. In one aspect, thedevices and methods disclosed herein are used for closing abdominalincisions when primary suture closure is not feasible due to loss ofabdominal muscle and/or fascia. In some embodiments, the devices andmethods disclosed herein are used for midline incision closure followinga surgical procedure. In another aspect, the devices and methods areused as a treatment for ventral or incisional hernia, e.g., fortreatment of midline incisional hernia. In various embodiments, themethods and devices of the present disclosure can be used forprophylactic treatment, e.g., to prevent incisional hernia. In someembodiments, the methods and devices of the present disclosure can beused to treat preexisting abdominal wall defects or to assist in closureof incisions or hernias where insufficient abdominal tissue is present.

In one exemplary embodiment of the present disclosure, incision closureis performed using an implant comprising an elongate element and atleast one sheet connected to the elongate element along a longitudinalaxis of the elongate element. When performing an incision closure, theelongate element is positioned along the incision line, and the at leastone sheet is positioned on the anterior and/or posterior side of theabdominal muscles surrounding the incision. In one embodiment, thebiomechanical properties (e.g., the tensile strength, compressivestrength, torsional strength, toughness of the material, etc.) of theelongate element are equal to that of the at least one sheet. In anotherembodiment, certain biomechanical properties (e.g., tensile strength,stiffness, tear strength) of the elongate element are greater than thatof the at least one sheet. The relative mechanical properties of theelongate element and the sheet may be determined based on the specificapplication of the implant. For example, in one embodiment, a strengthof the elongate element is twice that of the at least one sheet. Inanother embodiment, a strength of the elongate element is at least threetimes that of the at least one sheet.

In one exemplary embodiment, the sheet comprises a porous biologicalmaterial. In some embodiments, the sheet comprises a collagenousmaterial. In certain embodiments, the sheet comprises an acellulartissue matrix, which may support revascularization and repopulation ofthe implanted matrix with the patient's own cells to further strengthenthe treatment site and lower the risk of matrix dislodgement. In someembodiments, the acellular tissue matrix includes a dermal matrix. Inone such embodiment, the sheet is derived from human skin (e.g.ALLODERM®, LifeCell Corp, Branchburg, N.J.) that has been processed toremove both the epidermis and the cells that can lead to tissuerejection and graft failure, without damaging the dermal matrix. Inanother embodiment, the sheet is derived from porcine dermis (e.g.STRATTICE™, LifeCell Corp, Branchburg, N.J.), which is processed toremove cells and tissue antigens while maintaining the ability tosupport cellular growth and tissue regeneration and/or remodeling. Inanother exemplary embodiment of the present disclosure, the sheet of theimplant comprises a porous synthetic mesh (e.g., polypropylene, prolene,or polytetrafluroetheylene mesh). In one such embodiment, the syntheticmesh facilitates tissue incorporation into the implant.

In one exemplary embodiment consistent with the present disclosure, theelongate element is a cylindrical body comprising an immunologicallyinert and biocompatible material. The material may be a syntheticpolymer (such as, polypropylene, polytetrafluroetheylene, etc.) or anon-synthetic material. In one embodiment of the present disclosure, theelongate element comprises a biological mesh that is rolledconcentrically into a cylindrical structure. In one such embodiment, thebiological mesh comprises an acellular tissue matrix (such as, ALLODERM®or STRATTICE™).

In various embodiments consistent with the present disclosure, theelongate element and sheets can be produced from tissue that isallogeneic or xenogenic to a human recipient. Allogeneic sources may beobtained from living donors or cadavers. Xenogeneic sources can includea variety of different non-human mammals. For example, as noted above,one suitable biologic material for production of the sheets and elongateelement is STRATTICE™, which is a porcine-derived tissue matrix.However, other xenograft sources can be used.

Allogeneic or xenogenic tissues can be processed to remove antigensknown to elicit an immune response in the recipient. For example,various decellularization processes or enzyme treatments are known thatallow removal of cellular and/or extracellular antigens that may beimmunogenic. Further, in various embodiments, the tissues can be derivedfrom animals that are genetically modified or altered to have diminishedexpression of antigens known to be immunogenic in humans. For example,in one such embodiment, the tissues are harvested from anα1,3-galactosyltransferase (α1,3GT) deficient pig or other animal toprevent hyperacute rejection of the implant by the recipient. Differentmethods of producing α1,3GT deficient pigs have been previouslydescribed in Dai, Y. et al., “Targeted disruption of theα1,3-galactosyltransferase gene in cloned pigs,” Nat. Biotechnology 20,251-255 (2002), and Phelps, C. J. et al., “Production ofα1,3-galactosyltransferase-deficient pigs,” Science 299, 411-413 (2003),which are incorporated herein by reference.

In some embodiments of the present disclosure, the elongate element caninclude a strip or piece of connective tissue from an allogeneic orxenogeneic source. For example, suitable connective tissues can includeligament, tendon, and/or fascia.

In one exemplary aspect of the present disclosure, the prostheticimplant is used for treatment of a midline abdominal incision, which isa vertical incision made along the linea alba between the two rectusabdominis muscles of the abdominal wall. In certain patients, the lineaalba may be absent or shifted from the abdominal midline due toabdominal wall defects. In such cases, the midline incision may beperformed along the anatomical midline of the abdominal wall, instead ofthe linea alba (if present). When closing the midline incision, theelongate element is positioned along the incision, and the at least onesheet is positioned over and/or under the rectus abdominis musclessurrounding the incision. The linea alba located in the abdominalmidline is a three-dimensional composition of connective tissue fibersfrom abdominal wall muscles, which plays a significant role instabilizing the abdominal wall. Use of a connective tissue material forthe elongate element, therefore, facilitates reliable closure of themidline incision and provides good aesthetic results. The elongateelement may, however, comprise any biological or synthetic material thatis immunologically compatible, is structurally and functionally similarto the linea alba, and facilitates duplication of the abdominal wallphysiology.

FIG. 1A shows an exemplary embodiment of a prosthetic implant 10 inaccordance with the present disclosure. FIG. 1B illustrates across-sectional view of the embodiment depicted in FIG. 1A taken alongline AA′. FIG. 1C depicts an alternate configuration of implant 10, andFIG. 1D is a cross-sectional view of the configuration depicted in FIG.1C taken along line BB′. Implant 10 comprises an elongate element 12 andat least two sheets 20 a and 20 b connected to the outer surface ofelongate element 12 on opposite sides of a longitudinal axis 14 of thecentral element. The sheets can be connected to elongate element 12using absorbable biological sutures (e.g. catgut, polyglactin, etc.),non-absorbable sutures (e.g. nylon, polypropylene, etc.), surgicalstaples, clips, or tissue adhesives. In one embodiment, as illustratedin FIG. 1A-1D, sheets 20 a and 20 b are connected to elongate element 12along the midline of the sheets. In such an embodiment, attachment ofsheets 20 a and 20 b to elongate element 12 divides the sheets into twohalves.

As depicted in FIGS. 1A-1D, sheet 20 a forms two flaps 21 a and 22 a ofequal dimensions upon attachment to element 12. Similarly, sheet 20 bforms two symmetrical flaps 21 b and 22 b. Sheets 20 a and 20 b may,however, be connected to elongate element 12 along any longitudinalaxial line of the sheets. In some embodiments consistent with thepresent disclosure, the flaps formed by connection of the sheets to theelongate element are asymmetrical.

In one embodiment, sheets 20 a and 20 b extend along a planesubstantially parallel to longitudinal axis 14, as illustrated in FIGS.1A and 1B. In such an embodiment, sheets 20 a and 20 b form two pocketsbetween flaps 21 a and 21 b and 22 a and 22 b, respectively, whenattached to elongate element 12. In an alternate embodiment, sheets 20 aand 20 b are folded away from elongate element 12, as illustrated inFIG. 1C and FIG. 1D, such that sheets 20 a and 20 b form two pocketsbetween flaps 21 a and 22 a and 21 b and 22 b, respectively.

Although sheets 20 a and 20 b are generally shown in a rectangular formin the figures, the depiction is only for illustrative purposes, and anysuitable size, shape and form can be used depending upon thespecifications of the surgical procedure and the extent of repairnecessary. In one embodiment, as illustrated in FIGS. 1A and 1C, thelengths of both sheets 20 a and 20 b are equal to the length of elongateelement 12. The lengths of elongate element 12 and sheets 20 a and 20 bare selected to span the length of the incision. However, in someembodiments, the length of implant 10 may be shorter than the length ofthe incision, depending on the extent of the restorative procedure andthe amount of reinforcement required in the abdominal wall. The geometryof implant 10 may be tailored to the intended application prior to thesurgery or during the surgical procedure. Further, in some embodimentsconsistent with the present disclosure, implant 10 comprises multiplesheets that are superimposed, or layered, to provide additionalreinforcement to the abdominal wall. The multiple sheets may bechemically or physically bonded to each other to facilitate positioningof implant 10 in the abdominal wall.

The method of performing an incision closure using prosthetic implant 10will now be described with reference to FIGS. 2A and 2B, whichillustrate the anatomy of the abdominal wall and an abdominal midlineincision outline, respectively. FIG. 2A shows a cross-sectional view ofthe abdominal wall comprising the rectus abdominis muscles 50, lineaalba 52, transversalis fascia 54, peritoneum 56, subcutaneous fat 58,skin 60, anterior layer of fascia 62 and posterior layer of fascia 64.FIG. 2B shows a midline incision 100 made through linea alba 52 betweenrectus abdominis muscles 50 and around umbilicus 66. Further, althoughthis method is described for midline closure, the method of incisionclosure disclosed can be applied for the treatment of any incision typeand/or to treat other structural abdominal wall defects.

During closure of midline incision 100, elongate element 12 of implant10 is positioned along the line of incision, and sheets 20 a and 20 bare positioned on the anterior and/or posterior sides of rectusabdominis muscles 50. Prior to the positioning of elongate element 12,potential spaces for the placement of the sheets 20 a and 20 b may becreated by dissection around the incision using a blunt instrument orthe surgeon's fingers. In one embodiment of the present disclosure, whenthe midline incision is above the arcuate line of the abdomen, spacesbetween the rectus abdominis muscles 50 and the anterior and posteriorlayers of fascia 62, 64 may be dissected for placement of the sheets 20a and 20 b. Elongate element 12 is then aligned with the midlineincision, and the sheets are inserted into the dissected pockets, asshown in FIG. 3A. Below the arcuate line, the posterior layer of fascia64 is not present, and therefore, the posterior flaps 21 b and 22 b arepositioned in spaces dissected between rectus abdominis muscles 50 andtransversalis fascia 54 or positioned to cover the transversalis fascia54 or peritoneum 56.

In another embodiment of the present disclosure, as illustrated in FIG.3B, sheets 20 a and/or 20 b overlay anterior layer of fascia 62, and onthe posterior side, the sheets are positioned between posterior layer offascia 64 and transversalis fascia 54 or overlying the transversalisfascia or peritoneum.

In some patients receiving implant 10, the anterior and/or posteriorlayers of fascia 62, 64 may be partially or completely lost due tomultiple prior surgeries, necrotizing infections, and/or othercomplications. In such cases, sheets 20 a and 20 b are simply positionedin proximity to the rectus muscles 50. If the fascia is partiallypresent, it may be abraded by the surgeon to expose the rectus musclesand release blood to initiate the wound healing process. The sheets thenspontaneously anneal with the rectus muscles. When the sheets comprise abiological matrix material, the sheets may be remodeled by the patient'sown cells, thereby, facilitating rapid integration of the sheets intothe repair site.

In another embodiment of the present disclosure, elongate element 12 isaligned with the midline incision in accordance with the configurationshown in FIGS. 1C and 1D, such that the rectus muscles 50 are supportedbetween flaps 21 a and 22 a of sheet 20 a on one side of the incision,and flaps 21 b and 22 b of sheet 20 b on the other side.

Following the placement of sheets 20 a and 20 b into the treatment site,the sheets are secured to the rectus muscles. The sheets 20 a and 20 bcan be secured using a variety of anchoring systems, including, forexample, sutures, staples, clips, and/or tissue adhesives. As usedherein, securing the sheets 20 a and 20 b to the rectus muscles will beunderstood to include securing the sheets 20 a and 20 b directly to therectus muscles and to include securing the sheets to a layer of theabdominal wall adjacent to the rectus muscles, including a layer ofrectus fascia, transversalis fascia, or peritoneum.

In some embodiments, as shown in FIGS. 3A and 3B, the sheets are securedusing sutures that pass through a portion of the sheet, the rectusabdominis muscles, and/or the posterior and/or anterior layer of fascia.The suturing needle is inserted through layers of the abdominal wall andsheets 20 a and 20 b, and then reversed to retrace the path through theabdominal wall layers and sheets. The free ends of sutures 70 are tiedtogether on the anterior side of sheets 21 a and 22 a. In someembodiments, as shown in FIG. 3A, the sutures may be tied anterior tothe anterior layer of fascia 62. Sufficient care is taken to avoidincorporation of visceral or other structures into the suture line.Sutures are placed along the line of incision to ensure completereapproximation of the abdominal wall. The frequency of the lateralsuture anchors is determined by the surgeon during the procedure.

In some embodiments, the reapproximation is performed using continuousor interrupted loop sutures 80, as shown in FIG. 4. Suture loops 80incorporate elongate element 12 in order to secure the fascia and orrectus muscles to the elongate element 12. This applies tension to theabdominal wall structures and draws them medially to close the incision.Loop sutures 80 may be used in conjunction with interrupted sutures 70,as described above, or alone.

FIG. 5 is a flowchart diagramming the steps of treating an abdominalwall following a midline incision using implant 10. As noted, the methodcan be used for prophylactic treatment of the incision (e.g., to preventdehiscence) or to facilitate closure of incisions or defects that aredifficult to close with sutures alone.

The first step in closing the midline incision includes optionallycreating potential spaces for the placement of sheets 20 a and 20 b onboth sides of the midline incision (step 510) if needed. In one aspectof the present disclosure, spaces between rectus muscles 50 and anteriorlayer of fascia 62 are dissected for placement of the sheets on theanterior side of the ventral abdominal wall, and spaces between rectusmuscles 50 and posterior layer of fascia 64 or transversalis fascia 54are created for placement of the sheets in the posterior side of theabdominal wall. In another aspect, the sheets are positioned overanterior layer of fascia 62 and below posterior layer of fascia 64. Insuch a procedure, the surgeon creates spaces between fascia 62 andsubcutaneous fat 58 on the anterior side on the abdominal wall. On theposterior side, spaces between fascia 64 or rectus muscles 50 andtransversalis fascia 54 may be dissected. Alternatively, on theposterior side, the sheets 20 a and/or 20 b may be placed between thetransversalis fascia and the peritoneum. Step 510 may not be required ifan adequate region for attachment of the sheets to rectus abdominismuscles is already present or if a patient is suffering from substantialloss of fascia 62, 64.

The second step comprises positioning elongate element 12 of implant 10along the midline incision (step 520) to begin approximation of thewound margins. In one exemplary embodiment, the cranial end of elongateelement 12 is aligned with the superior end of the midline incision, andthe caudal end of the implant is aligned with the inferior end of theincision. The size of the implant could be adjusted by the surgeoneither before the procedure, or during the placement of the implant.

The next step is the insertion of the sheets into the spaces created instep 510 (step 530) or on the appropriate sides of the rectus muscles ifno spaces have been created.

Next, the sheets are secured in place (step 540). As described above,the sheets can be secured using, sutures, staples, clips, tissueadhesives, or other suitable means. The method of securing the deviceand the suturing technique are determined by the surgeon during theprocedure. This is followed by closure of the skin using eithernon-absorbable or absorbable sutures. Alternatively, surgeons may usesurgical staples for skin closure due to speed of application and easeof removal.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

1. A device for treating an incision, hernia, or abdominal wall defect,comprising: an elongate element having a cross-section and alongitudinal axis perpendicular to the cross-section; a first sheetconnected to the elongate element extending parallel to the longitudinalaxis on a first side of the elongate element, the first sheet foldingaway from the elongate element to form a first portion and a secondportion of the first sheet, the first and second portions of the firstsheet forming a first opening therebetween; and a second sheet connectedto the elongate element extending parallel to the longitudinal axis on asecond side of the elongate element opposite to the first side, thesecond sheet folding away from the elongate element to form a firstportion and a second portion of the second sheet, the first and secondportions of the second sheet forming a second opening therebetween. 2.The device of claim 1, wherein the first and second openings are sizedand dimensioned to receive a portion of a rectus abdominus muscle suchthat the first portion of the first sheet covers an anterior portion ofa first rectus abdominus muscle and the first portion of the secondsheet covers an anterior portion of a second rectus abdominis muscle,and the second portion of the first sheet covers a posterior portion ofthe first rectus abdominus muscle and the second portion of the secondsheet covers a posterior portion of the second rectus abdominis muscle.3. The device of claim 2, wherein when positioned within the firstopening, the first rectus abdominis muscle is separated from theelongate element by the first sheet, and when positioned within thesecond opening, the second rectus abdominis muscle is separated from theelongate element by the second sheet.
 4. The device of claim 1, whereinthe first sheet and the second sheet each comprises a tissue matrixhaving the ability to support cellular growth and tissue regeneration.5. The device of claim 1, wherein the first and second portions of thefirst sheet are symmetrical, and the first and second portions of thesecond sheet are symmetrical.
 6. The device of claim 1, wherein thefirst and second portions of the first sheet are asymmetrical, and thefirst and second portions of the second sheet are asymmetrical.
 7. Thedevice of claim 1, wherein the elongate element defines a cylindricalstructure that extends along the longitudinal axis.
 8. The device ofclaim 7, wherein the elongate element comprises an acellular tissuematrix rolled concentrically into the cylindrical structure.
 9. Thedevice of claim 1, wherein the first and second sheets each comprises aporous biocompatible matrix and the elongate element has a strength thatis at least twice a strength of the first sheet and the second sheet.10. The device of claim 1, wherein the first and second sheets eachcomprises a porous biocompatible matrix and the elongate element has astrength that is at least three times a strength of the first sheet andthe second sheet.
 11. The device of claim 1, wherein the first sheet andthe second sheet each comprises a non-synthetic mesh.
 12. The device ofclaim 1, wherein the first sheet and the second sheet each comprises anacellular tissue matrix.
 13. The device of claim 12, wherein the firstsheet and the second sheet each comprises a dermal matrix.
 14. Thedevice of claim 1, wherein the elongate element comprises a piece ofconnective tissue.
 15. The device of claim 14, wherein the connectivetissue comprises a porcine tendon.
 16. A method of closing a midlineincision, comprising: providing an implant including (i) an elongateelement having a cross-section and a longitudinal axis perpendicular tothe cross-section, (ii) a first sheet connected to the elongate elementextending parallel to the longitudinal axis on a first side of theelongate element, the first sheet folding away from the elongate elementto form a first portion and a second portion of the first sheet, thefirst and second portions of the first sheet forming a first openingtherebetween, and (iii) a second sheet connected to the elongate elementextending parallel to the longitudinal axis on a second side of theelongate element opposite to the first side, the second sheet foldingaway from the elongate element to form a first portion and a secondportion of the second sheet, the first and second portions of the secondsheet forming a second opening therebetween; positioning the elongateelement along the midline incision; and positioning a portion of a firstrectus abdominus muscle in the first opening and positioning a portionof a second rectus abdominus muscle in the second opening such that thefirst portion of the first sheet covers an anterior portion of the firstrectus abdominus muscle and the first portion of the second sheet coversan anterior portion of the second rectus abdominis muscle, and thesecond portion of the first sheet covers a posterior portion of thefirst rectus abdominus muscle and the second portion of the second sheetcovers a posterior portion of the second rectus abdominis muscle. 17.The method of claim 16, further comprising creating spaces on theanterior and posterior sides of the first and second rectus abdominismuscles for placement of the first and second sheets.
 18. The method ofclaim 16, further comprising suturing the first and second sheets to thefirst and second rectus abdominis muscles.
 19. The method of claim 16,comprising inserting the first portion of the first sheet beneath ananterior fascia layer of the first rectus abdominus muscle and insertingthe first portion of the second sheet beneath an anterior fascia layerof the second rectus abdominis muscle.
 20. The method of claim 16,comprising inserting the second portion of the first sheet beneath aposterior fascia layer of the first rectus abdominus muscle andinserting the second portion of the second sheet beneath a posteriorfascial layer of the second rectus abdominis muscle.